Discussion

A good free full-text article is available to cover this terrain. In it, there is an excellent table, "Aetiology of pulmonary infections in HIV-infected patients". It also presents the incidence of the aetiology. Turns out, in 97% of cases the pulmonary infiltrates are infectious in nature. The bacterial pathogens are surprisingly mundane- its S.pneumoniae, H.influenzae and Legionella. Together they cover something like 60% of pulmonary infections. Pneumocystis accounts for another 20%, and viruses for 5%. Other fungal infections are surprisingly rare - 2% - and protozoal parasites represent only 0.5%.

Causes of diffuse pulmonary infiltrates in the AIDS patient, and a brief note on their specific treatment

Non-infectious:

Pulmonary oedema - PEEP and preload reduction

Diffuse alveolar haemorrhage - correction of coagulopathy

Malignant (eg. lymphangitis carcinomatosis) - dexamethasone

Autoimmune (vasculitis) - high dose steroids

Inflammatory - ARDS - lung-protective ventilation

Infectious:

Bacterial:

Streptococcus pneumoniae - ceftriaxone

Mycobacterium tuberculosis - standard cocktail

Mycoplasma pneumonia - azithromycin

Generally speaking, broad spectrum antibiotics which are narrowed when the pathogen is isolated

Viral

CMV - ganciclovir or foscarnet

VZV - acyclovir

HSV - acyclovir

Influenza - possibly oseltamivir

Human metapneumovirus - supportive management

Fungal:

Pneumocystis jirovecii - cotrimoxazole

This is the second most common cause of pneumonia, behind S.pneumoniae